By LE Construction · Published October 6, 2026
Every house moves a little. Concrete shrinks, wood dries, soil swells in wet winters and shrinks in dry summers. Most of the cracks you notice are a normal part of that. Some signs, though, point to movement that needs attention. Here is how to tell the difference.
Signs that are usually normal
- Hairline cracks in drywall at corners of doors and windows.
- Thin cracks in a concrete slab, garage floor or driveway.
- Small gaps at trim and caulk lines that open and close with the seasons.
These are common and usually cosmetic. Note them, and watch for change.
Signs worth investigating
- Cracks that grow. Mark the ends of a crack with a pencil and the date. If it lengthens or widens over months, it is moving.
- Cracks with offset. One side higher than the other, in drywall, stucco or concrete.
- Stair-step cracks in block or brick walls.
- Doors and windows that start sticking or will not latch, especially if it gets worse.
- Sloping or bouncy floors.
- Gaps between walls and ceilings or floors.
- Water pooling against the foundation or in the crawlspace.
Ventura County factors
Soils
Parts of the county have expansive clay that swells and shrinks with moisture, which moves slabs and footings. The Oxnard Plain has a mapped liquefaction hazard, which matters most in earthquakes.
Older raised foundations
Older homes in Santa Paula, Fillmore, Ventura and Ojai often sit on raised foundations, some with very old concrete. Crumbling concrete, missing anchor bolts and rotted sill plates are common findings in their crawlspaces. Fillmore saw how vulnerable older buildings are in the 1994 Northridge earthquake.
Drainage
Gutters that dump water at the foundation, patios that slope toward the house and planters against walls all put water where it should not be.
What to do
- Document what you see with photos and dates.
- Fix drainage first; it is often part of the cause.
- Get an engineer’s evaluation for significant or growing signs.
- Repair to the engineer’s design.
Retrofits and repairs
If your house is on a raised foundation with cripple walls, a seismic retrofit is a separate but related upgrade. A sound foundation is required for a standard retrofit. See our seismic retrofitting and foundations pages, and our comparison of raised foundations and slabs.
Frequently asked questions
Are hairline cracks in a concrete slab a sign of foundation failure?
Usually not. Concrete shrinks as it cures, and thin cracks in slabs and garage floors are common and normally cosmetic. Cracks that widen over time or show one side higher than the other deserve a closer look.
Who should I call about a possible foundation problem?
For significant signs, such as widening cracks, floors that keep sloping or doors that keep getting worse, start with a structural engineer for an evaluation. A contractor then repairs to the engineer's design.
Can Ventura County soils cause foundation movement?
Parts of the county have expansive clay that swells when wet and shrinks when dry, and the Oxnard Plain has a mapped liquefaction hazard. Poor drainage around a house makes soil movement worse.
Is a foundation problem the same as needing a seismic retrofit?
No. A seismic retrofit braces cripple walls and bolts a raised-floor house to its foundation to prepare for earthquakes. A foundation problem is damage or movement in the foundation itself. Some houses need both, and a crumbling foundation must be addressed before a standard retrofit.